1. Field of the Invention
The present invention relates to a medical device for placement at a predetermined location within a vessel of the human body, and more particularly, relates to a collapsible embolization device that is delivered by a catheter at a predetermined position within the vessel to thereby embolize a defect in the blood vessel, such as an aneurysm.
2. Description of the Prior Art
For many years flexible catheters have been used to place various devices within the vessels of the human body. Such devices include dilatation balloons, radiopaque fluids, liquid medications and various types of occlusion devices such as balloons and embolic coils. Examples of such catheter devices are disclosed in U.S. Pat. No. 5,108,407 to Geremia, et al., entitled, xe2x80x9cMethod And Apparatus For Placement Of An Embolic Coilxe2x80x9d and U.S. Pat. No. 5,122,136 to Guglielmi, et al., entitled, xe2x80x9cEndovascular Electrolytically Detachable Guidewire Tip For The Electroformation Of Thrombus In Arteries, Veins, Aneurysms, Vascular Malformations And Arteriovenous Fistulas.xe2x80x9d These patents disclose devices for delivering embolic coils at predetermined positions within vessels of the human body in order to treat aneurysms, or alternatively, to occlude the blood vessel at the particular location.
Coils, which are placed in vessels, may take the form of helically wound coils, or alternatively, may be random wound coils, coils wound within other coils or other such coil configurations. Examples of various coil configurations are disclosed in U.S. Pat. No. 5,334,210 to Gianturco, entitled, xe2x80x9cVascular Occlusion Assembly and U.S. Pat. No. 5,382,259 to Phelps, et al., entitled, xe2x80x9cVasoocclusion Coil With Attached Tubular Woven Or Braided Fibrous Coverings.xe2x80x9d Embolic coils are generally formed of radiopaque material, such as platinum, gold, tungsten or alloys of these metals. Often times several coils are placed at a given location in order to occlude the flow of blood through the vessel by promoting thrombus formation at the particular location.
In the past, embolic coils have been placed within the distal end of the catheter and when the distal end of the catheter is properly positioned the coil may then be pushed out of the end of the catheter, with for example a guidewire, to release the coil at the desired location. This procedure for placement of the embolic coil is conducted under fluoroscopic visualization such that the movement of the coil through the vasculature of the body may be monitored and the coil may be placed in the desired location.
Other embolization devices, such as detachable balloons, are placed in vessels or aneurysms. These balloons usually take the form of an inflatable elastic balloon with a valve assembly for sealing the balloon when a desired inflation is reached. Examples of various detachable balloons are disclosed in U.S. Pat. No. 4,517,979 to Pecenka, entitled, xe2x80x9cDetachable Balloon Catheterxe2x80x9d and U.S. Pat. No. 4,545,367 to Tucci, entitled, xe2x80x9cDetachable Balloon Catheter And Method Of Use.xe2x80x9d Detachable balloons are generally formed of a flexible polymer and are inflated with a radiopaque solution for visualization under fluoroscopy. Often several balloons are used to fill the aneurysm space. These balloons do not generally conform to the aneurysm space thereby leaving unoccupied space leading to an incomplete aneurysm embolization. Often times a balloon valve may leak thereby causing other balloons to shift position, which may in turn, occlude the parent artery leading to severe complications.
Included in the list of aneurysm embolization devices are stents. Stents have been used to treat some aneurysms, however, most stents are fairly rigid and cannot access tortuous vascular anatomy. A more flexible stent with the ability to access tortuous vessels is disclosed in U.S. patent application Ser. No. 09/052,402 to Hieshima, et al., entitled, xe2x80x9cStent Aneurysm Treatment System and Method,xe2x80x9d filed Mar. 31, 1998. Since most stents are designed to open a partially blocked vessel, a substantial amount of material is used to support the vessel wall. In treating many aneurysms this additional material is unnecessary and may have deleterious consequences by blocking small vessels or perforators.
The present invention is directed toward an aneurysm embolization system for use in placing an aneurysm embolization device at a predetermined site within a vessel which includes an elongated, flexible catheter having proximal and distal ends and a through lumen, a push rod and an aneurysm embolization device. The catheter is positioned within the vasculature with the distal end at the neck of an aneurysm. The aneurysm embolization device is collapsed and slidably positioned within the lumen of the catheter. The push rod is slidably positioned in the catheter proximal to the aneurysm embolization device. As the push rod is moved towards the distal end of the catheter the push rod engages the aneurysm embolization device causing it to exit the distal end of the catheter lumen and to expand into position across the neck of the aneurysm to thereby embolize the aneurysm.
In accordance with another aspect of the present invention, the aneurysm embolization device is comprised of a stabilizing member and an occluding member fixedly attached to the stabilizing member. The aneurysm embolization device is formed from a flexible resilient material, which is sufficiently flexible to be passed through tortuous vasculature. The stabilizing member when expanded generally forms a circular loop. The occluding member when expanded generally takes the form of a wire scaffold positioned across the neck of the aneurysm and generally extends around only a portion of the interior circumference of a blood vessel.
In accordance with still another aspect of the present invention, aneurysm embolization device is comprised of a superelastic nickel titanium alloy.
In accordance with still another aspect of the present invention, aneurysm embolization device is comprised of a radiopaque material.
In accordance with still another aspect of the present invention, the stabilizing member of the aneurysm embolization device takes the form of a semicircle.
In accordance with another aspect of the present invention, the aneurysm embolization device is comprised of first and second stabilizing members and an occluding member fixedly attached between the stabilizing members. The aneurysm embolization device is formed from a flexible resilient material, which is sufficiently flexible to be passed through tortuous vasculature. The first and second stabilizing members when expanded generally form a circular loop. The occluding member when expanded generally takes the form of a wire scaffold positioned across the neck of the aneurysm.
In accordance with another aspect of the present invention, the occluding member of the aneurysm embolization device comprises a cover, which is expanded into position across the neck of an aneurysm.
In accordance with another aspect of the present invention, the occluding member cover of the aneurysm embolization device takes the form of a fabric mesh.
In accordance with another aspect of the present invention, the occluding member cover of the aneurysm embolization device takes the form of an expandable foam.
In accordance with another aspect of the present invention, deployment means are utilized within the catheter to advance the generally cylindrical collapsible aneurysm embolization device through the catheter and position the expanded aneurysm embolization device within the vessel across the neck of an aneurysm.